Arsenal were left sweating when Bukayo Saka was withdrawn against Sheffield United on Sunday with a thigh muscle injury.
The 19-year-old dropped to the ground in pain midway through the second half after an incident in which he did not make contact with any other player.
Saka was unable to continue and had to be replaced by Willian in the 69th minute.
What was said?
When asked about Saka's condition in his post-game press conference, Arsenal boss Mikel Arteta said: “I don’t know. He had to come off. He had a discomfort in his thigh.
"It is the last thing that we need, because we are missing some big players at the moment and we don’t want to lose another one. So hopefully it is not that serious.”
Asked if Saka could be ready for Thursday's Europa League match against Slavia Prague, Arteta responded: "Let’s see how he develops in the next few days.”
What could Saka's injury mean?
The England international has become one of Arsenal's most important players this season; only Granit Xhaka has played more minutes among the club's outfield players.
Arsenal moved up to ninth in the Premier League table with a 3-0 win over the Blades on Sunday, but a European place still appears far off.
The Gunners' main concern this season has become the Europa League, and they will desperately hope Saka will be fit for Thursday's quarter-final clash against Slavia Prague.
Arsenal drew with the Czech outfit 1-1 in their home leg on Thursday, putting them at a disadvantage heading into the second leg in Prague.
The club are also suffering from some key injuries at the back, with Kieran Tierney and David Luiz out for several weeks.
How has Saka fared this season?
Saka has cemented his status as one of the Premier League's top young players in 2020-21, tallying six goals and seven assists in 37 total appearances.
The teenager has also earned four caps for England as he chases a place at Euro 2020 this summer.